Documentation: fix vdso_standalone_test_x86 on 32-bit

vdso_standalone_test_x86 needs -lgcc_s to build succesfully on 32bit.

Signed-off-by: Peter Foley <pefoley2@pefoley.com>
[ Fixed missing separator issue reported by Paul Bolle <pebolle@tiscali.nl> ]
Signed-off-by: Jonathan Corbet <corbet@lwn.net>